1. Field of the Invention
The subject invention relates generally to enclosures for heat-generating electrical components. More particularly, it relates to an improved heat-dissipating housing for power amplifiers and the like.
2. Description of the Related Art
The prior art recognizes the use of power or performance amplifiers and the like to modify audio frequency signals generated by a sound system. With such known amplifiers, audiophiles can listen to high-fidelity sound reproductions of music and speech, even in adverse conditions such as inside a moving vehicle or water craft.
In the past, electronic circuit boards, such as those found in power amplifiers, were conventionally mounted on open racks. When installed in such a manner, the electronic boards were exposed to ambient air, dust, humidity, and other conditions which adversely affected the characteristics, performance, and useful lives of the circuit boards and associated components. As a result, inventions were directed at overcoming the disadvantages of these prior mounting methods.
One such invention is disclosed in U.S. Pat. No. 4,656,559, dated Apr. 7, 1987, to Fathi. The Fathi invention provides a one-piece metal tube with internal grooves to support circuit boards and circuit members, and external ridges to maximize radiation of heat from inside the tube. Fathi also provides two removable cover plates for attaching to the open ends of the tube to form a closed compartment inside the tube. A particularly advantageous feature of the Fathi invention is the relative ease with which the circuit boards and components can be inserted and removed from the grooves inside the tube.
A similar invention is disclosed in U.S. Pat. No. 5,130,891, dated Jul. 14, 1992, to Christie. The Christie invention presents an amplifier housing assembly which is particularly useful for automobile stereo systems. The housing assembly basically comprises an amplifier enclosure for containing the amplifier components and a mounting plate which bolts to a stationary surface inside the vehicle. The primary advantage of the Christie invention is that the amplifier can be easily removed when in need of servicing.
Another related invention appears in U.S. Pat. No. 5,285,500, dated Feb. 8, 1994, to Mantz. Mantz discloses an amplifier unit adapted for use in a vehicle which has an opening through which circuitry can be changed inexpensively by a consumer, thereby enabling the basic operating characteristics of the amplifier unit to be modified to suit the consumer's desire.
In still another related invention, U.S. Pat. No. 5,521,792, dated May 28, 1996, to Pleitz, et al. discloses a simplified amplifier housing and mounting system. The Pleitz invention substantially eliminates observable and unfinished screw heads, limits the affects of stray magnetic flux and ground loop noise, minimizes the costs associated with replacing housing and mounting components, and can be manufactured and installed inexpensively.
All of the housings disclosed in the aforementioned inventions are equipped with ridges and valleys which serve to increase the surface area of the particular housing so that the housing operates as an efficient heat sink for the electronic circuits and associated components inside the housing compartment. None of the aforementioned inventions, however, do anything more than increasing the surface area to provide a means for dissipating heat from the electronic circuits and associated components contained inside the housing compartment.
The need to provide additional cooling for the electronic circuits and associated components contained inside a housing compartment, such as those found in the aforementioned inventions, has become increasingly important as typical environments for such housing compartments have changed significantly. For example, in the case of power amplifiers for automobiles, suitable hidden space within an automobile has become less available as more compact automobiles are designed and more existing hidden space is required to house new or improved factory installed option hardware. Where suitable hidden space is not available, add-on automotive equipment, such as a power amplifier, must be located in relatively less suitable locations such as the trunk of the automobile.
One problem with installing a power amplifier in the trunk of an automobile is that the power amplifier is subject to higher temperatures and humidity, which can adversely affect the performance and durability of the electronic circuits and components contained inside the power amplifier housing. Moreover, most consumers would rather not utilize precious trunk space with bulky audio equipment. Therefore, under these and similar circumstances, there exists a need for additional cooling within a limited amount of space to keep the electronic circuits and associated components from overheating.
The cooling problem discussed above is partially addressed in U.S. Pat. No. 5,742,478, dated Apr. 21, 1998, to Wu, et al. Wu discloses a housing for a power converter that dissipates heat from the top of the housing via a heat conductor plate which is connected to the housing. The heat conductor plate allows heat to be quickly and uniformly released from the housing into the surroundings. As in all of the inventions cited above, the housing in Wu is equipped with ridges and valleys which increase the surface area of the housing so as to improve the heat sink efficiency of the housing. The heat dissipation effect is further reinforced by an exhaust fan which draws air into the housing.
The present invention is clearly distinguishable from the Wu invention on several accounts. First, the present invention discloses a fan that not only draws air out of the housing, but also forces air into the housing, whereas, the Wu invention merely discloses an exhaust fan which only draws air into the housing. Second, the present invention is configured so that the cooling air makes several passes within the housing before exiting, thereby decreasing the overall size of the invention for each square inch cooled. The Wu invention does not disclose this feature. Other distinguishing features of the present invention over the Wu invention and the remainder of the prior art will be apparent to those skilled in the art after review of the following description of the preferred embodiments.